In order to measure accurately the position of movable machine component relative to each other, preferably applied optical position measuring device.This optical position measuring device comprises: one or more light scanning units, and these scanning elements are connected with the first machine component; And one or more measurers, these measurers are connected with the second machine component, and wherein the second machine component is movable with respect to the first machine component.By by means of scanning element optical scanning (a plurality of) measurer, can determine and mobile relevant position signalling and and then the relative position of definite machine component.Measurer can be designed as the rule of one dimension or also can be designed to two-dimentional scale plate at this.In a possible application, the scanning element of position-measurement device is arranged on movable machine component, for example worktable, and it must be positioned at machining tool below, wherein, is furnished with workpiece to be processed on worktable.This workpiece should by worktable in plane of motion (XY-plane) along two main movement shaft X, Y is movably, and other degree of freedom (along Z axis, move, it is perpendicular to XY-plane; Around X-, the rotation of Y-and Z-axle) be fixed or only should adjust slightly.In being parallel to the plane of plane of motion, the scale plate of one or more two dimensions of position-measurement device is arranged on machine, and scanning element must can measure them.Place around each machining tool regularly scale plate Ci position.
The main task of this position-measurement device is, at least along main movement shaft X, and the one-movement-freedom-degree x of Y, y aspect and at the rotary freedom R around Z-axle
zposition and the situation of machine component determined in aspect.At this, relate to so-called 3-DOF-below and measure (DOF=degree of freedom).In addition for high-precision application, may need, detect all six-freedom degrees of each machine component.This may be also additionally along the one-movement-freedom-degree z of Z-axle and around the rotary freedom R of Y-or X-axle
x.Refer to that in this case so-called 6-DOF-measures.
This being for example used in semi-conductor industry, illumination-or the system of inspection unit (machining tool) below positions wafer (workpiece) is known by US2007/0195296A1.Worktable T in this machine is furnished with position-measurement device at this, and this position-measurement device has according to US7, and the scanning element E1-E4 of four combinations of 573,581 B2 is as schematically illustrated in Fig. 1 of the application in this.By each scanning element E1-E4, produced sweep signal position measurements in other words, it comprises with respect to the both direction component scale plate being scanned, scanning element position:
-along the predetermined direction in the plane of scale plate; The position measurements making progress the party is marked as Y below
-along the distance perpendicular to scale plate; This position measurements is marked as Z below, and corresponding range observation is measured as Z-.
Therefore according to US7, the scanning element of 573,581B2 can be regarded as having the scanning element of the direction of measurement in plane of motion XY and have the combination perpendicular to the scanning element of the direction of measurement Z of plane of motion XY.
Scanning element E1-E4 is installed on the Si Ge angle of worktable T and as can be seen in Fig. 1 and favours two main movement shaft X, Y alignment.Therefore, scanning element is calculated position measurements according to alignment direction
Or position measurements
In addition, each scanning element E1-E4 provides about its information along the distance with respect to the Z-axle of scale plate position measurements in other words.
Scanning element E1-E4 measures with respect to four scale plate M1-M4 adjacent one another are, that place in rhombus in known device, as this is as shown in Fig. 2.In addition the consistance that, the axle in Fig. 1 and 2 is described is at random selected.Central slot at scale plate device forms Liao compare great region B.Machining tool, for example illumination-or inspection unit be positioned at here.When machine moves, below and while that one of four scanning element E1-E4 can temporarily be positioned at the region B of fluting formation do not provide measured value.However, machine location also can be determined in this case exactly, because three scanning elements that mesh with scale plate M1-M4 are enough for determining the six-freedom degree of worktable T.
The precision of corresponding machine is the disturbing factor by below and being affected fatefully also:
-scale plate M1-M4 distortion (static or slowly change when machine moves, so-called " Drift(gradually changes) ", conventionally by temperature fluctuation, caused)
-be placed with proper vibration and the vibration of worktable T or the machine component of workpiece thereon.
Workpiece is larger, and described disturbing factor is just more important, because for machine component and scale plate compared with large, the same design proposal that more difficult is by strengthening suppresses vibration and distortion.Yet if the measurement data about the current foment of scale distortion and machine component vibration is provided, can take suitable measure to compensate or vibration damping.
This vibration of machine component shows as the distortion of vibration machine component, for example worktable.It causes in the machine component of (supposition) rigidity the deflection with respect to the scanning element E1-E4 disposed thereon of the position of its hypothesis.Therefore, the actual position of position machine component, that consideration is directly obtained from the measured value of scanning element E1-E4 when not trembleing and machine component is inconsistent.In addition, the machining tool position being gone out by machine component-position calculation, i.e. for example illumination-or the position of inspection unit with respect to workpiece, be that wafer can not accurately be determined, because the common vibration of workpiece and machine component and correspondingly bending.
Survey the known possibility of vibration of machine component based in frequency range be applied to scanning element value in the power on machine component or the analysis of the corresponding time history of analyzing.For this reason for example with reference to US2011/0317142A1.Obtain like this, about the information of the machine component bending that caused by flutter mode, can in the adjusting of actuator, be removed like this, the error of position that caused by vibration, machining tool reduces greatly with respect to workpiece.
Only yet this vibration of the time series analysis based on scanning element-measured value detects and compensates and has a series of shortcomings.
The vibration of machine component is not surveyed by measuring system machine is in service, but predicts by dynamic physical model, this model description the impact of external force for machine component.Physical model can be calculated or mechanical measurement is determined by theory.Therefore the little deviation of this model and actual mechanical property and the power effect for machine component not recording have directly caused the site error of machining tool with respect to workpiece.The prediction of model can not be detected when machine moves with respect to the deviation of actual performance.
In addition in described US2011/0317142A1, propose,, by measured value (and power) analyze for position signalling and vibration-signal be the wave filter based on processing the time course of this parameter.This wave filter is for example arranged in frequency space, as bandpass filter or notch filter.In order to implement this frequency, filter, time signal curve must be known by the order of magnitude that trembles period of oscillation in a time interval.Therefore sort signal is processed and has forcibly been caused certain inertia or stand-by period of the regulating system within the frequency band corresponding to vibration at least.Just in accelerator fast or in the trial of the vibration in the short time at active suppression, therefore can expect, the regulating system of reacting slow is disadvantageous.
Summary of the invention
The object of the invention is to, realize a kind of position-measurement device, by this position-measurement device, except the 3-DOF-of the attitude of machine component determines, can also realize determining of crooked moment as far as possible machine component, that caused by vibration.
This object is had the position-measurement device of feature described in claim 1 and is realized by a kind of.
According to the favourable enforcement variant of position-measurement device of the present invention, in the feature of dependent claims, draw.
Position-measurement device according to the present invention is for detection of the relative position of two machine components, and it is arranged in plane of motion each other movingly at least along the first direction of primary motion and the second direction of primary motion.It comprises: at least one measurer, and this measurer is arranged on the first machine component; At least six scanning elements, scanning element is arranged on the second machine component and at plane of motion this measurer of optical scanning at least two direction of measurement.At this, each direction of measurement is corresponding at least two scanning elements; In addition, the non-point symmetry type of scanning element of a direction of measurement of the difference in plane of motion with respect to the center arrangement of the second machine component.
Also possibly, be provided with at least three other scanning elements, this scanning element is designed for and detects two machine components along the relative position of another direction, and wherein, this direction is pointed to perpendicular to plane of motion.
Advantageously, scanning element is not arranged on common connection straight line with common direction of measurement in plane of motion.
Can propose, that is:
-by two axles that are perpendicular to one another and erect in plane of motion, that intersect in the center of two machine components, form the cartesian coordinate system with four quadrants, and
-at least two quadrants, every at least two scanning elements are arranged with identical respectively direction of measurement.
Alternatively also can propose, that is:
-by two axles that are perpendicular to one another and erect in plane of motion, that intersect in the center of two machine components, form the cartesian coordinate system with four quadrants, and
-at least three quadrants, every at least two scanning elements are arranged with identical respectively direction of measurement.
Finally also can propose, that is:
-by two axles that are perpendicular to one another and erect in plane of motion, that intersect in the center of two machine components, form the cartesian coordinate system with four quadrants, and
-in all four quadrants, every at least two scanning elements are arranged with identical respectively direction of measurement.
This external this likely, the scanning element being arranged in the quadrant of diagonal angle positioned opposite all has respectively identical direction of measurement.
In addition can propose, be furnished with another scanning element at least three quadrants, it is the relative position along another direction for detection of two machine components, and wherein, this direction is pointed to perpendicular to plane of motion.
Likely, finally at least one scanning element of the direction of measurement of plane of motion with for the scanning element of the direction of measurement perpendicular to plane of motion, be jointly integrated in the scanning element of combination.
According to position-measurement device of the present invention therefore can:
-for detection of a plurality of degree of freedom of the machine component of arranging movingly, and
-for detection of the vibration of machine component.
In addition, can be for according to position-measurement device of the present invention, detect the error of the measurer using.
According to position-measurement device of the present invention, therefore can realize the common vibration that detects machine component of moment.At this, unlike the prior art particularly, measured value-analysis that need to be in the longer time period.Unwanted stand-by period in machine adjustments system or the reaction of reacting slow can be avoided, because the information about the deviation that is subject to vibration restriction of machine component is provided without delay.
Additional advantage is, the crooked measurement that is subject to vibration restriction of machine component is now directly according to carrying out on the measurement point of the scanning element of position-measurement device of the present invention.Determine current when crooked, therefore needn't forcibly review again come from the input of machine component high with the prediction that may be inadequate dynamic model.
Finally, by measure according to the present invention, also drawn a kind of possibility, expanded the maximum moving area of total system, and do not needed to increase applied measurer for this reason.Therefore expanded that region that machine component can move therein and locate.
The extra measured value obtaining can also be for calibration system, for example for surveying possible distortion or the error of scale plate.
To according to before the describing according to three of three position-measurement devices of the present invention specific embodiments of Fig. 6-8, first in conjunction with the present invention, analyze the consideration of different theoretical sides.
Therefore every kind of changing pattern has caused the vibration distortion of the corresponding machine component of the form that characterizes this pattern.The changing pattern of the similar low-limit frequency that is designed to square machine component is exemplarily shown in Fig. 4 a-4e, wherein, is provided with smooth worktable as machine component, placed workpiece thereon.Fig. 4 a-4e illustrates respectively the height profile of machine component at this, i.e. its Z-shaped deflection.Except altitude line, in these accompanying drawings, also show arrow, the direction of this each gradient of arrow points.Independent, on the different point of machine component scanning element that install, position-measurement device by the distortion deflection of vibration.Therefore if the pattern of machine component is known, position measurements is by the bending of machine component, in the mode of position known, that depend on scanning element, is affected.
Figure 3 illustrates the mechanism of the little distortion of in main order machine component or worktable.Utilize reference number M to represent in the drawings measurer at this; C
0the worktable surface of expression in rest position, itself and measurer M have separated apart from d
mC.In this plane, at a P
0place is provided with scanning element A shown in broken lines.Scanning element A needn't forcibly be arranged in worktable surface C at this
0top, or rather, it also may be relevant to worktable surface C
0sink downwards and arrange.Scanning element A measures with respect to measurer M, as shown by vertically extending dot-and-dash line in the drawings in this.
In service at machine, change and facilitated now the table plane bending of the vibration on worktable surface in other words.In Fig. 3, for example show crooked worktable surface, it is there with C
vibrepresent.Vibration by occurring, also makes scanning element A move and tilt.The scanning element A being moved illustrates with solid line in the drawings.For smooth machine component, vibration mode can be understood to the variation of vibration of the height profile on machine component surface in main order.Scanning element A is lifted or declines with value δ Z along Z-axle by vibration; In addition cause scanning element A to tilt around X-axle with an angle, its in Fig. 3 with R
xrepresent.According to the design of direction of measurement and scanning element A, deviation δ Z and R
xwith respect to rest position, act on the position measurements producing of scanning element A.If inclination and movement that the characteristic of scanning element A is producing are known, what by vibration mode, caused can calculate the contribution of position measurements from the instantaneous deflection of machine component.If scanning element A shown in Figure 3 is for example the scanning element having along the direction of measurement of Y-axle, and the point of rotation of the centre of scanning element A to be positioned at measurer M upper, the position measurements that detected along direction of measurement Y based on machine component with value δ Z ≈ d
xbending and change.The middle point of rotation is interpreted as that at this that scanning element A can not cause the point of the variation of produced position measurements around the possible inclination of its generation.At this, also can abandon approaching with main order.Although deflection and the relation between position measurements at machine component are more complicated subsequently, can also in the category of geometric model, be calculated.
Iff the scanning element with direction of measurement is set in plane of motion, therefore can not measure machine component around the inclination of X-or Y-axle and the Z-position of machine component or can not be in linear order with plane of motion in one-movement-freedom-degree x, y distinguishes mutually.For the position of machine component and the 3-DOF-of location determine, at least three suitable scanning element position measurements also just must be provided, make can determine coordinate X thus the anglec of rotation R of Y and machine component
z; All position measurements that other provides can be for surveying vibration.Utilization comprises having X, and the 3+N of the direction of measurement in a Y plane scanning element can detect maximum 3 degree of freedom x, y, R subsequently
zand N flutter mode.
If at least three scanning elements with direction of measurement Z are yet provided, the 6-DOF-that can carry out machine component determines.Also just need in this case at least 6 suitable position measurements, to therefrom determine coordinate X, Y, the rotation R of Z and machine component
z; All position measurements that provide in addition can be for surveying vibration.Utilize for thering is the definite layout of 6-DOF-of 6+N scanning element altogether, can except 6 degree of freedom of (rigidity) machine component, also detect a maximum N flutter mode.
For analyzing the position measurements producing, the most important vibration mode of machine component must from mood analysis, for example computer be simulated or a kind of suitable measurement pre-determines.In order to analyze, equation system has for example been proposed, this system has been described the position measurements of expectation of the suitable layout of the scanning element on machine component.Each equation depends on that present vibration deflection and present machine component position reflected a position measurements.
Each flutter mode of utilizing mood analysis to find out represents a kind of additional degree of freedom.In form therefore also just utilization position-measurement device according to the present invention is measured (having the only scanning element of the direction of measurement in XY-plane of motion being restricted to) with a plurality of scanning elements at least one 3+N DOF-or 6+N DOF-measurement carried out, wherein, except the six-freedom degree of the body of rigidity, also measured N additional vibrational degree of freedom.Therefore can in fact detect the current bending of machine component, if its by the flutter mode detecting, is formed and can ignore other-common higher-pattern.
Described analytical approach can be alternatively and the analysis of the time curve of position measurements and the power that is applied on machine component is combined, for example also in the situation that application as method known in the US2011/0317142 A1 from the outset.
Therefore according to the invention discloses following extra feature:
If-need, can distinguish more degree of freedom than providing of the position measurements of scanning element, for example, by being divided into the mode of different natural frequencys,
-can introduce the information that comes from aforesaid measurement, for example, for reducing the fluctuation fast (noise) of result.
-likely, determine current amplitude and the phase place of the pattern of each detection.Can apply the time-derivative of deflection for this reason.Be included in this case the position measurements of at least one group of Measuring Time point early.
By amplitude information and phase information, can be aptly the control of the acceleration of machine component and/or suitable actuator be modulated, the vibration of machine component is suppressed on one's own initiative.According to different machines also possible that, the tracking of the compensation by machine component position or tool location reduce vibration on during process for the impact of workpiece.
If there is not the obvious vibration of machine component, only there are six position measurements to be required for determining six rigid body-degree of freedom.In addition (" redundancy ") position measurements of providing can for example be employed in this case, to machine is calibrated.In addition, for example can detection design the distortion of the measurer that is scale plate.This calibration can be undertaken by selecting suitably scan values to be independent of known vibration mode, for example, pass through with respect to the fixing scanning of the phase place of known vibration frequency or pass through the average of at least one vibration period.
Put it briefly so propose, by means of position-measurement device according to the present invention, as far as possible promptly determine or compensated the bending causing by vibration of machine component.
In the design phase of machine, for example, by finite element analogy or for finding out that the suitable measurement of N most important flutter mode carries out the pattern analysis of relevant machine component.
Self in service of machine, the analysis of machine component position and machine component vibration utilizes position-measurement device according to the present invention to carry out to detect the mode of 3+N or 6+N degree of freedom.
Therefore for example likely, by means of input, be coupled to the machine component acceleration in engine control or by means of the control of the suitable actuator for machine component, apply the power of vibration suppression.
In addition likely, for the vibration of compensate for residual, follow the tracks of machine component or machining tool.
Scanning element being arranged in this and should advantageously selecting in position-measurement device according to the present invention, to be as far as possible optionally relevant to pattern to be detected, and guarantees large moving range.In order to make input and cost keep less, should in position-measurement device according to the present invention, apply the least possible scanning element.Yet in principle should be able to be by detecting at least three important flutter mode according to the design proposal of the selection of position-measurement device of the present invention.
According to Fig. 6-8, describe according to the specific embodiment of position-measurement device of the present invention below.In order more preferably to understand according to the solution of the present invention, the layout of eight scanning element E1-E8 in a position-measurement device has been described according to Fig. 5 in advance, they are shown as improvement with respect to prior art, however for pursued, for the detection of machine component-vibration, be not also most suitable.
As started explanatorily, corresponding position-measurement device can be applied in for the manufacture of in semi-conductive machine; It is used herein to and detects two objects relative position of machine component in other words, and they are along the first and second main movement shaft Y, and X arranges each other movingly.Corresponding machine component can be for example the fixing machine component of primary importance and machine component, for example worktable T that can be movable relatively.Worktable T can be along the first and second main movement shaft Y of orthogonal sensing, X location.On worktable T, can arrange workpiece, for example wafer, the machining tool location that it is fixing with respect to position.
Fixing machine component place, position is provided with measurer one or more two dimensions, that have the scale plate form of intersection grid disposed thereon in an embodiment, as for example shown in Figure 2 in it.At movable machine component, on worktable T, be provided with in other words a plurality of scanner head E1-E8 for optical scanning (a plurality of) measurer.Be relevant to the details of the concrete design proposal of possible optical scanning and scanning principle, for example can be with reference to US 5,573,581 B2 that described, applicant.
Worktable T is arranged in plane of motion, and this plane is below also referred to as XY plane.Not only in accompanying drawing in Fig. 5 but also below, all with rectangle, worktable T is shown simplifiedly: circular workpiece can be arranged in the S place, center of worktable T.Certainly, worktable T also can have interchangeable geometric configuration.
In the embodiment of Fig. 5, shown position-measurement device comprises eight scanning element E1-E8 that are arranged on worktable T altogether.At this, four scanning element E1, E3, E5 and E7 are arranged in the angle of rectangle.Four scanning element E1, E3, E5, the layout of E7 with respect to the center S point symmetry of the worktable T in plane of arrangement carry out; All four scanning element E1, E3, E5 and E7 have the first identical spacing d with respect to center S
Scanning element E1 on the angle being oppositely arranged respectively of the worktable T shown in rectangle and E5 be E3 and E7 parallel aligned in other words.This means, be arranged on wherein, for the grid sensing parallel to each other of optical scanning, make its direction of measurement separately identical.In two angles that are oppositely arranged, therefore measured position measurements
with in two other angles that are oppositely arranged, measured position measurements
For four scanning element E1, E3, each scanning element in E5 and E7, in the embodiment of Fig. 5, be provided with now other scanning element E2, E4, E6 and E8, it has at front four scanning element E1, E3, the direction of measurement of the parallel sensing on the worktable T in the plane of arrangement of E5 and E7.These four other scanning element E2, E4, the Y-coordinate of E6 and E8 as according to Fig. 5 visibly with respect to scanning element E1, E3, in E5HeE7 angle, the center S toward worktable T moves respectively.Four other scanning element E2, E4, therefore E6 and E8 have the second spacing d with respect to center S
2, it is less than the scanning element E1 being arranged in angle, E3, the first spacing d of E5 and E7
The machine component in other words symmetry characteristic of worktable T transmits with the form of proper vibration.As found out according to Fig. 4 a-4e, be relevant to worktable center of gravity in other words the point symmetry of center S present the symmetry of particular importance.If the mechanical realization of worktable (approx) has been realized point symmetry, the natural mode under point reflection also (approx) be (immovable) of straight line, or non-directional (except symbol, being all identical).
If the group of scanning element is arranged in the mode of described worktable symmetry each other symmetrically now, it is that (or non-directional) vibration mode of straight line is redundancy that the position measurements producing on it is relevant under symmetric deformation, because the signal of this vibration scanning element group that cause, that be mutually symmetrical of serving as reasons is identical (being all identical in other words except symbol).This redundancy is not supposed to, because it has reduced the quantity about the independent information of the present foment of worktable, it can utilize the scanning element of setting to find out.
It should be noted that especially this have three, in the vibration mode shown in Fig. 4 a-4c.Can find out, these three vibration modes are straight lines in point-symmetric situation.Therefore in position-measurement device according to the present invention, should arrange like this scanning element, avoid the point-symmetric layout of needed scanning element, be sensitive to be relevant to each this first three vibration mode.
According to the scanning element of the embodiment from Fig. 5, arrange it is highly symmetrical.The typical case that will note is now, two scanning element E1-E8 that arrange are continuously the below in one of a plurality of measurers not, but for example in the region at center freely with machining tool.At this, it can be for example scanning element E7 and the E8 in arranging according to the scanning element shown in Fig. 5.Scanning element E1-E6 remaining, that activate provides information below subsequently:
By three scanning element E1 in angle, E3 and E5, provide enough information, to find out 6 firm body-degree of freedom of worktable T.Remaining three scanning element E2, E4, E6 provides the additional information for vibration detecting.But, scanning element E1, E2 and E5, E6 arranges on point symmetry ground each other, that is to say by this scanning element E1, E2 and E5, the information that E6 provides is at least part of redundancy.Therefore, the layout of eight scanning element E1-E8 shown in Fig. 5 or desirable, to obtain the information about the maximum possible of the existing vibration of possibility.
With respect to the scanning element of Fig. 5 optimization, arrange and therefore according to first embodiment of position-measurement device of the present invention, according to Fig. 6, describe below.
Figure 6 illustrates first embodiment according to position-measurement device of the present invention, be designed to the machine component of movable worktable T, mode and the method with definition is furnished with six scanning element E11-E16 thereon.In Fig. 6, not shown corresponding fixing machine component, is furnished with at least one measurer thereon.Worktable T is along two direction of primary motion Y in plane of motion, and X arranges movably.As measurer, at this, can a plurality of scale plate M1-M4 be set as shown in Figure 2, they comprise respectively two-dimentional intersection grid, it can scan by means of scanning element E11-E16.By scanning element E11-E16, at this, carry out respectively along the direction of measurement MR1 of definition, the optical scanning of the measurer of MR2.Therefore each scanning element E11-E16 is assigned definite direction of measurement MR1, MR2.Direction at this by the definition in three dimensions is interpreted as direction of measurement MR1, MR2.At the time point of measuring, scanning element E11-E16 provides digital value, so-called positional value.Positional value is relevant to sensing in the coordinate ，Qi space of cartesian coordinate axes by direction of measurement MR1 corresponding to scanning element E11-E16, MR2 is given.Cartesian coordinate axes this needn't with above-mentioned direction of primary motion Y, X is superimposed.
In the present embodiment, the direction of measurement MR1 of scanning element E11-E16, MR2 extends along its longitudinal axis respectively particularly; Yet it but depends on the scanning theory of each optics in principle not forcibly in category of the present invention.For example can be with reference to US7 mistake described above, applicant, 573,581B2 aspect the design proposal of scanning element.
According in first embodiment of position-measurement device of the present invention, the scanning element E11-E16 of setting is at two direction of measurement MR1, and the upper optics of MR2 is scanned up to and lacks a measurer.Therefore as according to Figure 6 shows that three scanning element E11, E12, E15 is assigned the first direction of measurement MR1, and it is with respect to+45 ° of the first direction of primary motion Y upsets; Be three scanning element E13, E14 and E16 are assigned the second direction of measurement MR2, and it is with respect to-45 ° of the first direction of primary motion Y upsets.In the present embodiment, be each direction of measurement MR1, MR2 is assigned respectively three scanning element E11, E12, E15 or E13, E14, E16, at least essential in principle, in position-measurement device according to the present invention for each direction of measurement is assigned at least two scanning elements.
For the redundancy of inquiring into above avoiding when detecting first three vibration mode, according to the present invention, be designed to now, scanning element E11, E12, E15 or E13, E14, E16 arranges with respect to worktable T's or corresponding machine component center S in plane of motion for a direction of measurement MR1 or MR2 respectively non-point symmetry.Therefore for example in first embodiment illustrating, do not have at scanning element E11, E12, the layout aspect of E15 (the first direction of measurement MR1) is with respect to the point symmetry of center S.Scanning element E12 and E15 have the different spacing with respect to center S; Connection straight line between scanning element E11 and E15 extends without center S.Be that the second direction of measurement MR2 arranges other scanning element E13, E14, E16 similarly.
Therefore if position-measurement device according to the present invention is applied in for the manufacture of in semi-conductive machine, and the machine component with scanning element is the worktable with workpiece, scanning element conventionally can only be arranged in worktable edge near; Workpiece has been placed at center at worktable conventionally.For vibration detecting, this layout is preferred, and wherein, the scanning element of common direction of measurement is not all on the arris in worktable.At this, for example consider the vibration mode shown in Fig. 4 a.If the scanning element with identical direction of measurement is given for to the arris of the straight line of worktable, all position measurements of scanning element have changed for example identical value.Therefore this variation can not be different from the change in location (or it is around upset of the axle in plane of motion) of worktable.Therefore can be in position-measurement device according to the present invention maybe advantageously, the scanning element of direction of measurement is not all positioned on common straight line.
In shown first embodiment, for each direction of measurement MR1, MR2 is respectively equipped with three scanning element E11, E12, E15 or E13, E14, E16.For each direction of measurement MR1, the scanning element E11 that MR2 arranges, E12, E15 or E13, E14, E16 arranges like this at this, and scanning element E11-E16 is with identical direction of measurement MR1, and MR2 is not arranged on common connection straight line in plane of motion.
Two axle A that are perpendicular to one another in plane of motion in Fig. 6, have also been described
2, they intersect at S place, the center of worktable T.By this axle A
2therefore be designed with cartesian coordinate system, it has initial point and four quadrant Q1-Q4 in the S of center.According in first embodiment illustrating of position-measurement device of the present invention, at two quadrant Q1, in Q2, be furnished with each two scanning element E11, E12 or E13, E14; Its scanning element E11 in being arranged in quadrant Q1 or Q2, E12 or E13, have respectively identical direction of measurement MR1, MR2 in E14.If the quadrant Q1 arranging at diagonal line, Q3 or Q2, arranged scanning element E11-E16 in Q4, can also be advantageously, and they have respectively identical direction of measurement MR1, MR2.This means, scanning element E11 for example, the Q1 that E12 and E15 arrange at diagonal line, has identical direction of measurement MR1 in Q3; Similarly, scanning element E13, E14 and E16, at corresponding quadrant Q2, have identical direction of measurement MR2 in Q4.
It is favourable that this layout proves in consideration below:
For the rotation of testing platform T as far as possible well, must between scanning element E11-E16, provide enough large spacing.Therefore advantageously, not every scanning element E11-E16 is positioned at by axle A
2in one of the coordinate system strutting and same quadrant Q1-Q4.Meanwhile, although still should be able to realize large as far as possible moving range in the situation that of scale plate limited size, the wherein likely position measurement of worktable T.These two requirements can meet, and for this reason, as described above, in two of described coordinate system different quadrant Q1-Q4, need identical direction of measurement MR1, at least two scanning element E11-E16 of difference of MR2.Identical direction of measurement MR1, two scanning element E11 of MR2, E12 or E13, even if E14 has also guaranteed location positioning when two scanning elements are not below a scale plate.
Except arrange, there is the direction of measurement MR1 in the plane of motion of worktable T, outside the scanning element E11-E16 of MR2, can also be arranged on according in position-measurement device of the present invention, at least three other-that unshowned-scanning element is arranged in worktable T is upper, by it, can realize along the detection of the relative position of the worktable T of another axle; Conventionally it is Z axis at this, and this axle points to perpendicular to plane of motion and can cause working table movement along this axle equally machine is in service.By this way and method, all 6 translations that subsequently can testing platform-and rotary freedom.Preferably, therefore the layout of this additional scanning element carries out like this, in the quadrant Q1-Q4 shown at least three Fig. 6, places this scanning element.
Particularly advantageously also be, there is the direction of measurement MR1 in plane of motion, the scanning element E11-E16 of MR2 with for the additional scanning element of the direction of measurement perpendicular to plane of motion, be jointly integrated in the scanning element of combination.
The demonstration that is similar to Fig. 6 according to second of position-measurement device of the present invention embodiment is shown in Figure 7.Substantially only illustrated for the difference in the ratio of first embodiment below.
Again be provided with six scanning element E21-E26, they are arranged on the upper or corresponding machine component of worktable T with mode and the method for definition.
As found out with reference to the accompanying drawings, at least three quadrant Q1-Q3 of described coordinate system, be furnished with identical direction of measurement MR1, difference two scanning element E21/E22, E23/E24 and E25/E26 of MR2.The advantage of this layout is, all scanning element E21-E26 can far arrange with respect to the center S of worktable.Can realize good especially vibration detection thus, guarantee to retain the larger mobile route of worktable T simultaneously.
Preferably, the quadrant Q1 arranging at diagonal line, Q3 or Q2, arranged scanning element E21-E26 in Q4, it has identical direction of measurement MR1, MR2; It is current at quadrant Q1, Q3 and scanning element E21, and E21, is guaranteed in E25 and E26.In this case, at the quadrant Q1 being oppositely arranged, Q3 or Q2, be noted that especially in Q4 and in the layout of the scanning element with respect to center S, do not realize point symmetry.In the illustrated embodiment, this demand is for example satisfied, wherein, scanning element E21 arrange than scanning element E25 the center S closer to worktable T.
This embodiment also can be supplemented with additional scanning element as described above, and it is for detection of the working table movement along Z axis.
According to Fig. 8, illustrate according to the 3rd of position-measurement device of the present invention the embodiment subsequently, wherein again only inquire into respect to the difference in the ratio of the first two variant below.
Therefore, through the machining tool stretching, can in corresponding machine, cause following needs, that is, reserve the great region, center of scale plate.The scanning element that is positioned at machining tool below does not provide positional value.
Due to according to according to the 3rd of position-measurement device of the present invention the embodiment, in all four quadrant Q1-Q4 of above-mentioned coordinate system, be furnished with respectively at least two scanning element E31/E32, E33/E34, E35/E36, E37/E38, however still can keep position-and the vibration detection of expectation.If it is upper that machining tool is for example positioned at one of four quadrant Q1-Q4, can be all the time also according to the position measurements of the scanning element of other three quadrant Q1-Q4 of the first two examples measure.
Also be relevant to the effectively consideration of above-mentioned geometric aspects of this embodiment; Equally also can there is in this realization the expansion through inquiring into of additional scanning element.
Except illustrated variant, in category of the present invention, certainly also there are a plurality of other operational feasibilities.